Turbine engine fan casing and an assembly formed by such a casing and acoustic panels

ABSTRACT

A turbine engine fan casing of composite material including fiber reinforcement densified by a matrix is made as a single part with ribs that project from an inside face and/or from the outside face of the casing, each rib including a fiber reinforcement portion connected to the fiber reinforcement of a remainder of the casing by weaving or by stitching. On the inside, the ribs serve to mount acoustic panels to the inside face of the casing to form an assembly including a casing and acoustic panels. On the outside, the ribs enable equipment to be mounted on the casing.

BACKGROUND OF THE INVENTION

The invention relates in particular to a fan casing for a turbine engine, in particular an aviation engine.

In such a engine, the fan casing conventionally performs several functions. It defines the air inlet passage into the engine, it supports abradable material on its inside face facing the tips of the fan blades, it incorporates or supports a retention shield forming a trap for debris, it supports on the inside a soundwave absorber structure for acoustic treatment at the inlet to the engine, and on its outside face it supports various pieces of equipment such as harnesses, pipework, and other units.

It is well known to make a fan casing out of fiber-and-matrix composite material, generally comprising fibers and an organic matrix. Thus, Document EP 1 961 923 describes making such a casing by densifying a fiber preform obtained by winding superposed layers of a three-dimensionally woven texture of varying thickness and incorporating preform portions for the retention shield and for flanges at the upstream and downstream ends of the casing.

It is also well known to perform acoustic treatment by fastening acoustic panels on the inside face of the casing in the downstream portion thereof and/or in its upstream portion on one or both sides of an abradable coating. In conventional manner, the panels are in the form of juxtaposed sectors each extending over a fraction of the inside periphery of the casing, and the panels are fastened to the casing by means of inserts incorporated in the panels and by means of screws.

Fastening acoustic panels in that way presents several drawbacks. It requires the use of a large number of parts (inserts and screws), and it requires holes to be drilled in the casing. Likewise, fastening a plurality of pieces of equipment on the outside face of the casing by means of screws requires a large number of holes to be drilled. Unfortunately, with a casing that is made of composite material, repeatedly drilling the casing can harm the mechanical properties of the composite material.

OBJECT AND SUMMARY OF THE INVENTION

An object of the invention is to avoid such drawbacks, and for this purpose the invention proposes a turbine engine fan casing made of composite material comprising fiber reinforcement densified by a matrix and shaped as a single part with at least one rib that projects from the inside face or the outside face of the casing, the casing being characterized in that each rib comprises a fiber reinforcement portion that is connected to the fiber reinforcement of the remainder of the casing by weaving or by stitching.

Thus, one or more ribs suitable for use in mounting acoustic panels or other pieces of equipment on the inside or outside face of the casing are themselves formed with the casing during its fabrication.

In its longitudinal direction, the or each rib preferably extends substantially axially over a fraction of the axial dimension of the casing.

Advantageously, the fiber reinforcement is formed by a woven texture wound in superposed layers, and the fiber reinforcement portion of the or each rib is secured to the inner or outer layer of the texture by weaving.

According to another of its aspects, the invention provides an assembly made up of a fan casing and acoustic panels fastened to the inside face of the casing, in which assembly the casing is made of composite material comprising fiber reinforcement densified by a matrix and is formed as a single part with ribs that project from the inside face of the casing and that extend axially over a fraction of the axial dimension of the casing, each rib comprising a fiber reinforcement portion that is connected to the fiber reinforcement of the remainder of the casing by weaving or by stitching, and the acoustic panels are housed between the ribs and are fastened thereto.

In an embodiment of the casing and acoustic panel assembly, the fiber reinforcement is formed by a woven texture wound in superposed layers, and the fiber reinforcement portion of each rib is secured to the inner layer of the texture by weaving.

In an embodiment of the casing and acoustic panel assembly, the casing is formed as a single part also including at least one rib that projects from the outside face of the casing and that includes a fiber reinforcement portion connected to the remainder of the fiber reinforcement of the casing by weaving or by stitching.

The casing may carry at least one piece of equipment fastened to such a rib projecting from the outside face of the casing.

In another aspect, the invention also provides a turbine engine fitted with a fan casing or with an assembly as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood on reading the following description given by way of non-limiting indication and with reference to the accompanying drawings, in which:

FIG. 1 is a highly diagrammatic view of an aviation turbine engine;

FIGS. 2, 3, and 4 are highly diagrammatic half- views in axial section of fan casings that can be made in accordance with the invention for a turbine engine of the kind shown in FIG. 1;

FIG. 5 is a fragmentary section view on plane V of FIG. 2;

FIG. 6 is a view on a larger scale of a detail of FIG. 5;

FIG. 7 is a fragmentary section view on plane VII of FIG. 4;

FIG. 8 is a flat view on a smaller scale of a multilayer woven texture for making a fiber preform for a fan casing such as that shown in FIG. 2, in an embodiment of the invention;

FIG. 9 is a larger-scale view in section on plane IX of FIG. 8;

FIG. 10 is a view similar to that of FIG. 9 showing a step in making a fiber preform from the texture of FIG. 8;

FIG. 11 is a diagrammatic radial section view showing a fan casing fiber preform shaped on tooling in order to make a fan casing of the invention;

FIGS. 12 and 13 are larger-scale views of details of FIG. 11;

FIG. 14 is a highly diagrammatic fragmentary view in section of the FIG. 11 tooling;

FIG. 15 is a fragmentary view in radial section showing another embodiment of a fiber preform for a fan casing of the invention; and

FIG. 16 is a diagrammatic radial section view showing another fan casing fiber preform shaped on tooling in order to make a fan casing of the kind shown in FIGS. 3 and 7.

DETAILED DESCRIPTION OF EMBODIMENTS

The invention is described below in the context of its application to a fan casing for an airplane turbine engine. As shown diagrammatically in FIG. 1, such a turbine engine comprises, from upstream to downstream in the flow direction of the gas stream: a fan 1 arranged at the inlet of the engine; a compressor 2; a combustion chamber 3; a high pressure (HP) turbine 4; and a low pressure (LP) turbine 5. The turbines 4 and 5 are coupled respectively to the compressor 2 and to the fan 1 via respective coaxial shafts. The engine is housed in a casing having a plurality of portions corresponding to different ones of its elements. Thus, the fan 1 is surrounded by a fan casing 10 that may support on its outside face various pieces of equipment such as harnesses, pipework, and other units (not shown).

As shown in FIG. 2, the casing 10 presents flanges 13 and 14 at its ends, and in its portion situated facing the tips of the blades 11 of the fan it presents extra thickness forming a retention shield 15. The flanges 13 and 14 serve to connect the fan casing to other pieces of equipment upstream and downstream. The retention shield 15 constitutes a trap for centrifugally-projected debris in order to prevent it from passing through the casing and reaching other portions of the airplane.

Also, in its portion situated facing the tips of the blades 11, the casing 10 has an abradable coating 12 on its inside face. In known manner, the coating 12 may be made up of juxtaposed panels that are fastened to the casing 10 and lined with an abradable material, e.g. as described in Document EP 2 088 290.

Still in known manner, the casing 10 is provided on its inside face with at least one soundproofing coating. In the embodiment of FIGS. 2, 5, and 6, the soundproofing coating is formed by a set of acoustic panels 20 arranged in the downstream portion of the casing 10 between the abradable coating 12 and the downstream end of the casing, whereas in its upstream portion, between its upstream end and the abradable coating 12, the casing 10 is shaped so as to act, together with the inside surfaces of the abradable coating 12 and of the acoustic panels 20 to define an air inlet passage having a wall that is substantially continuous.

In the embodiment of FIGS. 3 and 4, two soundproofing coatings are provided, one made up of a set of acoustic panels 20 in the downstream portion of the casing 10, as in FIG. 2, and the other made up of a set of acoustic panels 20′ located in the upstream portion of the casing 10 between its upstream ends and the abradable coating 12, the inside surfaces of the panels 20′ of the abradable coating 12 and of the panels 20 defining the air inlet passage.

Each panel 20, 20′ of a set of acoustic panels extends over a portion of the inside periphery of the casing 10, with a set of acoustic panels comprising four or six panels, for example. As is well known, the panels 20, 20′ may be constituted by a honeycomb structure 21, 21′ arranged between an outer skin 22, 22′ pressed against the inside face of the casing 10 and an inner skin 23, 23′ with multiple perforations, the honeycomb being made up of cells defined by walls extending substantially radially between the skins. By way of example, reference may be made to Document FR 2 613 773.

The casing 10 is made of composite material comprising fiber reinforcement densified with a matrix. By way of example, the reinforcing fibers are made of carbon, glass, aramid, or ceramic. The matrix may be an organic matrix, e.g. an epoxy, a bismaleimide, or a polyimide polymer.

The fiber reinforcement may be formed by winding superposed layers or turns of a fiber texture made by three-dimensional weaving or multilayer weaving and shaped so as to obtain a fiber preform having a shape that corresponds to the shape of the fan casing that is to be made, the fiber preform being densified while being held in shape by means of tooling. Document EP 1 961 923 describes an embodiment of such a fiber preform that forms a single piece with preform portions corresponding to the flanges 13, 14 and that is obtained from a multilayer woven texture of varying thickness in order to form a preform portion corresponding to the retention shield 15. Nevertheless, it should be observed that the preform portions corresponding to the flanges 13, 14 could be fabricated separately and connected to the remainder of the preform, e.g. by stitching. It should also be observed that the extra thickness corresponding to the retention shield 15 could be obtained by localized over-winding.

In accordance with the invention, the casing 10 is made as a single piece with one or more ribs projecting from the inside face and/or the outside face of the casing and serving advantageously for mounting acoustic panels and/or other pieces of equipment.

In the embodiment of FIGS. 2, 5, and 6, ribs 16 extend in the downstream portion of the casing 10 between the abradable coating 12 and the downstream end of the casing, the longitudinal directions of the ribs 16 being oriented axially. The ribs 16 are advantageously in the form of section-member bars, e.g. presenting a T-shaped profile. The number of ribs 16 corresponds to the number of acoustic panels 20 and by way of example, they are distributed regularly around the axis of the casing 10, with the panels 20 extending over the same angles. The panels 20 are arranged between the ribs 16. As shown in greater detail in FIG. 5, the inner skins 23 of the panels are extended along their axial edges so as to form rims 23 a that press against the flanges 16 a of the ribs 16 on the outsides of the flanges. The rims 23 a form setbacks that enable a continuous profile to be conserved for the air inlet passage. The panels 20 may be fastened using fastener members such as screws or rivets connecting the rims 23 a to the flanges 16 a of the ribs 16. The ribs 16 may present a profile of a shape other than a T-shape, so long as it is suitable for mounting the panels 20 in association with fastener members.

In the embodiment of FIGS. 4 and 7, the casing 10 also presents on its outside face ribs 17 having a T-shaped profile that are formed integrally with the casing and that extend axially over a fraction of the axial dimensions of the casing. The ribs 17 (only one is shown) serve to fasten various kinds of equipment, such as harnesses, pipework, and other units. The ribs 17 need not necessarily be of T-shaped profile, they may be of any desired profile, e.g. of L-shaped profile.

One way of making a fiber preform for a fan casing having preform portions corresponding to the ribs 16 that are secured to the remainder of the preform is described below with reference to FIGS. 8 to 10.

FIGS. 8 and 9 are highly diagrammatic views showing a multilayer woven texture 30 in the form of a strip having a first portion 31 comprising a set of layers of warp yarns C1 interlinked with weft yarns T1, and a second portion 32 comprising a set of layers of warp yarns C2. Arrow C in FIG. 8 indicates the warp direction. The first portion 31 is to form the casing preform portion that does not include ribs 16, with the preform portions that correspond to the ribs 16 coming from the second portion 32.

In FIG. 8, shaded zones 33, 34 of the first portion 31 of the texture 30 represent the portions of the texture 30 that, after shaping, are to constitute the preform portions of the casing that correspond to the flanges 13, 14, while the shaded zone 35 of the first portion 310 of the texture 30 represents the portion of the texture 30 that, after shaping, is to constitute the casing preform portion that corresponds to the retention shield 15. Outside the portion 35, the first portion 31 of the texture 30 may be of a thickness that is substantially constant, e.g. having four layers of warp yarns interlinked with five layers of weft yarns, as shown in FIG. 9, it naturally being possible for the numbers of layers of warp yarns and of weft yarns to be different. For reasons of convenience, the weft yarns are shown, in FIG. 9, as being in a staggered arrangement, each layer of warp yarns being made up of two half-layers that are shown as being mutually offset in the thickness direction. The multilayer weaving in this example is performed using an interlock weave, i.e. with warp yarns following identical paths, and with each of them interlinking weft yarns in a plurality of layers. Other multilayer weaves could be used, e.g. such as multi-satin or multi-plain weaves as described in document WO 2006/136755. In the portion 35, the thickness of the texture portion 31 may be increased by localized addition of layers of warp yarns and of weft yarns.

The second portion 32 of the texture 30 extends over a fraction of the width of the first portion 31 at a location corresponding substantially to the location of the ribs 16 relative to the upstream and downstream ends of the casing 10, and it has a length corresponding substantially to the axial dimension of the ribs 16. In the example shown, the second portion 32 has two layers of warp yarns that are linked to the first portion solely at the locations of the connections between the ribs 16 and the remainder of the casing 10, and that are linked to one another solely over lengths that correspond to the developed heights of the ribs 16 on either side of these connection locations. In FIG. 8, zones 36 defined by dashed lines illustrate the locations where linking is performed between the layers of yarns in the second portion 32 and between said second portion 32 and the first portion 31. Such zones are situated over only a segment of length L of the fiber texture 30 starting from one end thereof, the length L corresponding to the inside perimeter of the casing 10 level with the locations of the ribs 16. As described below, the shaping of the fiber texture 30 in order to form a casing fiber preform is performed by winding the fiber texture 30. The number of zones 36 is equal to the number of ribs 16, i.e. four in the example shown. Over the remainder of the fiber texture 30, i.e. beyond the segment of length L, there is no interlinking of the portions 31 and 32 nor is there any interlinking of the layers of warp yarns in the portion 32. It should be observed that the presence of weft yarns in the portion 32 of the fiber texture 30 could be limited to only those zones where there is interlinking of the layers of warp yarns of the portion 32.

In a zone 36, FIG. 9 shows how the warp yarns C2 of the portion 32 are linked with the weft yarns T2 of the portion 32 and with the weft yarns T1 of the portion 31, the multilayer weave being of the interlock type, for example.

In order to shape the casing fiber preform starting with the texture 30, the warp yarns of the second portion 32 are eliminated except in the zones 36. In each zone 36, on either side of the warp yarns of the portion 32 that are interlinked with the weft yarns of the portion 31, there then remain woven portions 361 and 362 that are separated from the portion 31 by non-interlinked zones 361′ and 362′ (FIGS. 9 and 10). The woven portions can then be folded out (arrows f) in order to be brought side by side so as to form a portion constituting a preform for a rib 16.

FIGS. 11 and 12 show tooling suitable for shaping a fiber preform 50 for a casing by winding the fiber texture 30. A mandrel 40 is made up of substantially annular sectors 42 having axially extending edges that come into contact with parts 43 that contribute to imparting an angle shape to the preform portions 56 of the ribs 16, after the portions 361 and 362 have been unfolded. Additional parts 44 are placed between the axial edges of the sectors 42 and they bear against the bases of the ribs 16, the sectors 42 presenting a radial dimension that is greater than that of the ribs 16. The parts 43 and 44 serve to shape the preforms 56 of the ribs 16, the parts 44 also serve to provide the tooling 40 with sealing on the inside. The parts 44 may be held in position by means of bridges (not shown) bearing against their exposed faces and fastened to the circumferential ends of the sectors 42 on the inside, e.g. by screw fastening.

After forming a first turn or layer of fiber texture 30 having the preform portions 56 for the ribs 16, the fiber texture is wound on the mandrel 40 so as to form one or more superposed turns or layers, with the fiber texture 30 then being constituted by no more than its first portion 31. The number of turns or layers is a function of the desired total thickness, given the thickness of the fiber texture 30. As shown in FIG. 13, in the terminal portions 37, 38 at its longitudinal ends, it is possible to give the portion 31 of the fiber texture 30 thickness that increases progressively from the longitudinal ends, and the length of the fiber texture 30 may be selected in such a manner that the terminal portions are diametrically opposite so as to avoid notable extra thickness at the ends of the wound fiber texture.

As shown in FIG. 14, the sectors 42 are shaped to impart the desired profile to the inside face of the casing 10 and to form preform portions for flanges. A fiber preform 50 is thus obtained that has a shape matching the shape of the casing 10 that is to be made.

By way of example, the preform 50 may be densified by being impregnated with a composition that is a precursor for the desired matrix, e.g. a resin. It is possible to use a well-known impregnation process of the resin transfer molding (RTM) type, with the preform 50 being held between the tooling 40 and complementary tooling (not shown) pressed against its outside surface. After the resin has cured, the densified preform can be extracted from the tooling and finishing machining may optionally be performed on the casing.

In the example shown in FIG. 11, the beginning and the end of the first turn or layer of wound texture 30 are situated between two preform portions for ribs 16.

In a variant, the beginning and the end of the first turn or layer of the texture 30 may be at the location of a preform portion for a rib 16, the corresponding zone 36 then being shared as two similar half-zones situated at the ends of the segments of length L of the fiber texture 30.

FIG. 15 shows a variant embodiment of the fiber texture that makes it possible, after winding, to obtain a preform for a casing 10 having ribs 16 incorporated therein. In this variant, a fiber texture in the form of a strip comprising no more than the portion 31 of FIGS. 8 and 9 is made by three-dimensional or multilayer weaving, and preform portions for the ribs are formed separately from woven fiber texture and are connected to the first portion 31 of the texture 30, e.g. by stitching or by implanting yarns. In the example shown, each rib preform portion 36′ is made up of two strips 361′ and 362′ that are side by side and folded along a longitudinal edge so as to form flanges 361′a, 362′a that are fastened to the portion 31 by stitching. The fiber preform is shaped by means of tooling as described above for the preform 50.

Naturally, in the embodiment of FIG. 3, the panels 20 and the panels 20′ could be mounted in similar manner using ribs that are incorporated in the casing and obtained as described above for the ribs 16. A fiber preform for the casing is then preferably made with rib preform portions extending continuously from a location corresponding to that upstream ends of the panels 20′ to a location corresponding to the downstream ends of the panels 20. The central portion of the ribs in the gap between the locations of the panels 20′ and 20 is then eliminated during final machining of the casing after the preform has been densified.

The description above relates to making and shaping a fiber preform suitable for incorporating ribs 16 in the fan casing for the purpose of mounting acoustic panels on the inside of the casing.

It is possible to proceed in similar manner for making and shaping a fiber preform making it possible to incorporate one or more ribs in the fan casing that extend axially and that are for use in mounting equipment other than acoustic panels, whether on the inside or on the outside of the casing.

In particular, it is possible to make a fan casing preform that incorporates first preform portions for ribs for use in fastening acoustic panels on the inside, and second preform portions for ribs that are for use in fastening equipment on the outside, as for the casing shown in FIGS. 4 and 7.

FIG. 16 shows such a fiber preform 50′ shaped by means of tooling with preform portions 56′ for ribs 16 for fastening acoustic panels and preform portions 57′ for ribs 17 for fastening equipment on the outside of the casing, the preform 50′ differing from the preform 50 by the additional presence of the preform portions 57′.

In order to obtain a preform 50′, it is possible to wind a woven multilayer texture in superposed turns e.g. on the same principle as that described with reference to FIGS. 8 to 10, but adding an additional set of layers of warp yarns at the side of the first portion 31 opposite from its side where the second portion 32 is located at the other longitudinal end portion of the portion 31, and with the necessary non-interlinking for obtaining the preform portion 57′ that, after unfolding and shaping, project from the outside of the last turn of the wound texture. In a variant, it is possible to attach the preform portions 56′ and/or 57′ by stitching, as shown in FIG. 15.

In order to shape the preform 50′, tooling 40 similar to that shown in FIG. 11 is used on the inside. On the outside, the tooling comprises a countermold having annular portions 45 and parts 46, 47 for shaping the preform portions 57′.

The preform 50′ is densified as described for the preform 50. 

1-7. (canceled)
 8. A turbine engine fan casing made of composite material, comprising: fiber reinforcement densified by a matrix and shaped as a single part with at least one rib that projects from an inside face or an outside face of the casing; wherein each rib comprises a fiber reinforcement portion that is connected to the fiber reinforcement of a remainder of the casing by weaving or by stitching.
 9. A fan casing according to claim 8, wherein the fiber reinforcement is formed by a woven texture wound in superposed layers, the fiber reinforcement portion of each rib being secured to an inner or outer layer of the texture by weaving.
 10. An assembly comprising: a fan casing; and acoustic panels fastened to an inside face of the casing; wherein the casing is made of composite material comprising fiber reinforcement densified by a matrix and is formed as a single part with ribs that project from the inside face of the casing and that extend axially over a fraction of an axial dimension of the casing; each rib comprising a fiber reinforcement portion that is connected to the fiber reinforcement of a remainder of the casing by weaving or by stitching; and the acoustic panels are housed between the ribs and are fastened thereto.
 11. An assembly according to claim 10, wherein the fiber reinforcement is formed by a woven texture wound in superposed layers, the fiber reinforcement portion of each rib being secured to the inner layer of the texture by weaving.
 12. An assembly according to claim 10, wherein the casing is formed as a single part also including at least one rib that projects from an outside face of the casing and that includes a fiber reinforcement portion connected to a remainder of the fiber reinforcement of the casing by weaving or by stitching.
 13. A turbine engine comprising a fan casing according to claim
 8. 14. A turbine engine comprising an assembly according to claim
 10. 